Maui windstorm and wildfires - Narrative (Details) $ in Thousands					1 Months Ended		2 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Nov. 04, 2024 claim plaintiff	Nov. 01, 2024 USD ($) installment claim lawyer	May 04, 2024 USD ($)	Aug. 08, 2023 USD ($)	Oct. 31, 2024 USD ($)	Feb. 08, 2024 claim	Jun. 08, 2024 claim	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)	Jul. 15, 2024 claim	Nov. 08, 2023 USD ($)
Public Utilities, General Disclosures [Line Items]
Regulatory assets								$ (314,247)		$ (314,247)		$ (294,804)
Property insurance policy limit				$ 500,000
Retention for property damages				$ 1,000
Settlement accrual								1,915,000		1,915,000		75,000
Excess liability insurance										16,000
Miscellaneous professional liability										0
Directors and officers liability insurance										130,000
Insurance Claims, Legal-Related Recoveries
Public Utilities, General Disclosures [Line Items]
Insurance reimbursement receivable								74,000		74,000
Indemnification Agreement
Public Utilities, General Disclosures [Line Items]
Amount agreed to contribute			$ 18,400
Tort-Related Legal Claims | Maui Windstorm and Wildfires
Public Utilities, General Disclosures [Line Items]
Litigation settlement, fee expense accrued								3,500		3,500
Maui Wildfire Negligence | Maui Windstorm and Wildfires
Public Utilities, General Disclosures [Line Items]
Excess liability insurance										165,000
Miscellaneous professional liability										25,000
Excess liability insurance, retention amount										300
Miscellaneous liability insurance, retention amount										1,000
Directors and officers liability insurance										145,000
Directors and officers liability insurance, retention										1,000
Shareholder Derivative Actions, Northern District Of California
Public Utilities, General Disclosures [Line Items]
Lawsuit claim filed | claim						3
Shareholder Derivative Actions, District Of Hawaii
Public Utilities, General Disclosures [Line Items]
Lawsuit claim filed | claim							2
Subsequent Event | Tort-Related Legal Claims | Maui Windstorm and Wildfires
Public Utilities, General Disclosures [Line Items]
Lawsuit claim filed | claim	750
Number of settlement agreements | claim		2
Number of lawyers representing individual plaintiffs | lawyer		30
Subsequent Event | Maui Wildfire Negligence | Maui Windstorm and Wildfires
Public Utilities, General Disclosures [Line Items]
Number of pending claims | claim	1
Subsequent Event | Spectrum Oceanic LLC | Maui Wildfire Negligence | Maui Windstorm and Wildfires
Public Utilities, General Disclosures [Line Items]
Lawsuit claim filed | claim	1
Subsequent Event | Subrogation Insurers | Maui Wildfire Negligence | Maui Windstorm and Wildfires
Public Utilities, General Disclosures [Line Items]
Number of cases filed by subrogation insurers | plaintiff	160
Subsequent Event | County Of Maui | Maui Wildfire Negligence | Maui Windstorm and Wildfires
Public Utilities, General Disclosures [Line Items]
Lawsuit claim filed | claim	1
Hawaiian Electric Company, Inc. and Subsidiaries
Public Utilities, General Disclosures [Line Items]
Settlement accrual, current liability								478,750		478,750		75,000
Settlement payments reserved										500,000
Settlement accrual								1,920,000		1,920,000
Settlement accrual, non-current liabilities								1,436,250		1,436,250		0
Hawaiian Electric Company, Inc. and Subsidiaries | Insurance Claims, Legal-Related Recoveries
Public Utilities, General Disclosures [Line Items]
Insurance reimbursement receivable								69,000		69,000
Hawaiian Electric Company, Inc. and Subsidiaries | Indemnification Agreement
Public Utilities, General Disclosures [Line Items]
Settlement accrual								14,500		14,500
Hawaiian Electric Company, Inc. and Subsidiaries | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Insurance recoveries					$ 700
Settlement accrual, current liability		$ 479,000
Natural Disasters and Other Casualty Events
Public Utilities, General Disclosures [Line Items]
Expected funding amount														$ 175,000
Expected beneficiary amount														$ 1,500
Number of claim forms | claim													35
Number of physical injury related claim forms | claim													12
Natural Disasters and Other Casualty Events | Maui Windstorm and Wildfires
Public Utilities, General Disclosures [Line Items]
Insurance recoveries								52,158	$ 75,000	83,610	$ 75,000	104,580
Natural Disasters and Other Casualty Events | Subsequent Event | Tort-Related Legal Claims | Maui Windstorm and Wildfires
Public Utilities, General Disclosures [Line Items]
Amount agreed to contribute		$ 1,990,000
Installment payments | installment		4
Discount rate		5.50%
Natural Disasters and Other Casualty Events | Subsequent Event | Total Defendants | Tort-Related Legal Claims | Maui Windstorm and Wildfires
Public Utilities, General Disclosures [Line Items]
Amount agreed to contribute		$ 4,040,000
Natural Disasters and Other Casualty Events | Hawaiian Electric Company, Inc. and Subsidiaries
Public Utilities, General Disclosures [Line Items]
Regulatory assets								(38,800)		(38,800)
Committed contribution to humanitarian fund								75,000		75,000
Natural Disasters and Other Casualty Events | Hawaiian Electric Company, Inc. and Subsidiaries | Maui Windstorm and Wildfires
Public Utilities, General Disclosures [Line Items]
Insurance recoveries								49,625	$ 75,000	75,973	$ 75,000	$ 98,613
Incremental expenses								1,200		8,900
Natural Disasters and Other Casualty Events | Hawaiian Electric Company, Inc. and Subsidiaries | Tort-Related Legal Claims | Maui Windstorm and Wildfires
Public Utilities, General Disclosures [Line Items]
Insurance receivable								$ 40,000		$ 40,000
Natural Disasters and Other Casualty Events | Hawaiian Electric Company, Inc. and Subsidiaries | Subsequent Event
Public Utilities, General Disclosures [Line Items]
Committed contribution to humanitarian fund		$ 75,000